Dichlorido(4,4′-dimethyl-2,2′-bipyridine-κ2 N,N′)zinc(II) acetonitrile monosolvate

In the crystal structure of the title compound, the central zinc(II) atom is surrounded by a bidentate 4,4′-dimethyl-2,2′-bipyridine ligand and two coordinating chlorides in a distorted tetrahedral shape with π–π stacking interactions contributing to the crystal packing.


Structure description
Over the last decade, metal complexes of 4,4 0 -dimethyl-2,2 0 -bipyridine have garnered significant attention due to their photophysical properties (Tamer et al., 2020;Queiroz et al., 2022), electrocatalytic activity (Ogihara et al., 2018;Taylor et al., 2018), and potential as antitumor agents (Amani et al., 2014). Recently, platinum complexes incorporating 4,4 0 -dimethyl-2,2 0 -bipyridine were found to be effective against several cancer cell lines, including L1210 murine leukemia, HT29 human colon carcinoma, and U87 human glioblastoma (Pages et al., 2015). Our research group interest currently lies in synthesizing metal complexes with applications in biological systems; as part of our research in this area, herein, we describe the synthesis and structure of the title complex, which promises to be a useful starting material in the synthesis of novel zinc(II) complexes.
The asymmetric unit contains one molecule of the title compound and one solvent molecule of acetonitrile. The zinc(II) atom exhibits a distorted tetrahedral cooordination environment defined by two pyridine nitrogen atoms from the 4,4 0 -dimethyl-2,2 0 -bipyridine ligand and two chlorido ligands (Fig. 1). The Zn-N bond lengths are in good agreement with the comparable bromide analog complex currently available in the CSD (version 5.43 with update June 2022; Alizadeh et al., 2010, refcode DURYAR) and with other 2,2 0 -bipyridine-based zinc(II) complexes (Khan & Tuck, 1984, refcode CEFFOI; data reports Hossienifard et al., 2011, refcode DAKMUZ;Nauha et al., 2016, refcode EMERAR;Khalighi et al., 2008, refcode POFKOL). Similar behavior is observed for the Zn-Cl bond lengths. The small bite angle N2-Zn1-N1 of 80.19 (7) reflects the distortion from the ideal tetrahedral coordination. Numerical data of relevant bonds and angles are presented in Table 1.
The title complex packs into layers extending parallel to the bc plane that are packed along the a-axis direction (Fig. 2). Contiguous pyridine rings showstacking interactions, with centroid-to-centroid distances (CgÁ Á ÁCg) alternating between 3.718 (1) Å and 3.725 (1) Å , and offset distances of 1. 166 and 1.191 Å ,respectively (Fig. 3). No other significant supramolecular interaction is present in the crystal packing of the title compound.

Synthesis and crystallization
Zinc(II) chloride (0.370 g, 2.71 mmol) was added to a methanol solution (40 ml) of 4,4 0 -dimethyl-2,2 0 -bipyridine (0.500 g, 2.71 mmol). After stirring for 30 min, the resulting suspension was filtrated to obtain a white precipitate of the title compound (0.470 g, 54%). Crystals suitable for X-ray diffraction were obtained by vapor diffusion of diethyl ether over a saturated acetonitrile solution of the title compound at 277 K.

Figure 2
Perspective view of the crystal packing of the title complex approximately along the b axis; H atoms are omitted for clarity.

Figure 3
Capped sticks representation of the title molecule showingstacking interactions (red). H atoms and acetonitrile molecule are omitted for clarity.

Figure 1
The structures of the molecular entities of the title compound with displacement ellipsoids drawn at the 50% probability level; H atoms are omitted for clarity.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2.

data-1
IUCrData ( where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.002 Δρ max = 0.47 e Å −3 Δρ min = −0.75 e Å −3 Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.